My lab does moorings. Engineers design
and build huge floats that sit on the surface, or just beneath it.
The wire that holds these floats in place will extend to the heavy
anchor on the ocean floor, with a set of instruments often spanning
the entire depth. We deploy these at sea, and recover them
months/years later. The return is a time series of selected
oceanographic quantities, for the entire water column, in one
location.
Prepping the floats
A couple of weeks back, we deployed and
recovered a series of moorings for our CORC Project (more at
http://mooring.ucsd.edu). In 90 hours, we deployed a glider, two
bottom and two subsurface moorings, recovered one subsurface and two
bottom-mounted instrument, and had zero relaxing transit. I'll
describe the deployments here, and touch on the recovery process in a
future post.
Moorings
Surface and subsurface moorings have
different designs, but similar deployment processes. The trick is to
get the entire 1-4 km of cable, instruments, chain, floats, and
anchor off of moving/bouncing boat without getting anything tangled.
Sometimes you have to stand on stuff
To start, we angle the boat so it is
roughly steaming towards the desired location. The large float is the
first thing in the water. For surface moorings, this is a huge
surface buoy, while subsurface floats are smaller. Instruments start
on the main float itself, and continue along the cable in carefully
determined intervals.
At the end of the wire, a couple
lengths of chain, more flotation, and finally the anchor (normally
railroad wheels) are lifted over the ship's edge. We continue to
steam to the desired location, with sometimes trailing 4km of wire,
floats, and instruments. Once the Chief Scientist gives the signal,
the anchor is dropped and pulls all to rest vertically in the water
column.
Anyways, watch a couple timelapses and
check out a bunch of photos.
This is the beginning of the first deployment. It lasted over 6 hours, was in ~3800 meters of water, and had a subsurface float that rested at about 50 meters below the surface.
This is the end of the first deployment, the anchor is about to drop when the camera card fills.
This is the (almost) entirety of the Second Deployment. It lasted only about 2.5 hours, was in 800 meters of water, and again the SD Card filled up right before the anchor drop.
Somethings Interesting:
--Our instruments use magnets to induce
tiny electric pulses in the wire that holds them in place. Similar to
Morse Code, this process transmits all the data from each instrument
to a single modem. The surface modem will transfer the data via
satellite; the subsurface modem is acoustic, and will transmit the
data to a passing glider, which will bring the data to the surface
within reach of the satellite.
--Our deck leader is a salty German who
has the uncanny ability to tell you exactly which box (of over 20)
holds each wrench, bolt, and wire length. Rumor has it his toes are
made of steel, and has no need for steel toed boots.
--Our lab is playing a large role in
the OOI Project, where 4 moorings systems will be put in 4 of the
roughest waters, essentially on the corners North and South America.
The deployments and recoveries will be nothing short of exciting.
Port Hueneme, in Oxnard
A ship, bigger than ours
Fully loaded, ready to depart
Some first years earned their sea legs
Full moon!!
Paul caught a fish; lab BBQ a week later
Pre-Deployment meeting; Chief Scientist in sneakers, Deck Leader in Shorts and Boots
First Instrument; it's covered in Copper to keep off Bio-Fouling
Location of GoPro Camera
Last set of floats with release.
Deck Leader
Deployment 2, surface floats.
Deck Leader, rolling a Cig
That's me
Our Bottom Releases are acoustic and let go only to a particular set of frequencies.
Last week was my first cruise with the new lab. As they specialize in moorings (longterm deployments of instruments for scientific use), we put two in the water and got one out.
First, we have to choose a specific spot to drop the anchor, in our case a set of 500 pound railroad wheels on a large metal post. Because of the weight of these objects, they will drop straight downward, pulling anything attached with them. After making a giant 'X' where we measure bottom topography, the spot is chosen by Uwe Send our Principle Investigator and Chief Scientist.
We allow the boat an hour long drift test which will go into calculations for where to start the deployment; we have over 3500 meters of cable, rope, instruments, and chain which we want to be pulled into that special location by the anchor when it drops. During this drift test, the float is being prepared, the instruments are being lined up, and we are all psyching ourselves up for the intense deployment about to take place.
Two Buoys to be Deployed on the New Horizon
The float is the first to go in, with multiple people holding multiple guidelines attached to multiple points on the buoy; while it floats, the buoy still weighs ~4200 pounds and swings where the waves take it if we aren't careful. Once in the water, the float is towed behind us as the boat chugs along at a comfortable 1-1.5 knots in order to avoid tangles. We slowly feed the wire out, placing sensors at preordained locations.
After 1000 meters of cable/rope/chain/instruments (or 4000 with the second buoy), we prepare to release the 5000 pound anchor. Dangerous pitching and rolling ensues, but with enough guidelines, the anchor makes it into the water, pulling the buoy as it falls.
Surveying the Goose-neck Clam Coverage
Somethings Interesting: -Recovery is not as exciting and a lot smellier; as the instruments near the water are pulled onboard, theyare covered with goose-neck clams, algae, and crabs attempting to defend their home.
-The longest "day" for me this cruise was the recovery and deployment at the second station. Each process takes about 8 hours, plus prep and a few CTD casts were thrown in for good measure; in 39 hours, I managed to escape for 5 hours of sleep.
-Following the cruise, I trained it north to Long Beach for an Irish Catholic Family Reunion (on my mother's side). This was my first age 20+ reunion with this family; a good time was had.
